class Father{
    constructor(){
        console.log('创建都要经过我');
    }
    toString(){
        console.log('实际上我是被定义在Father.prototype上的');
    }
}
let a1=new Father()

console.log(a1);
console.log(Object.getPrototypeOf(a1)===Father.prototype);
console.log(Object.getOwnPropertyNames(a1.__proto__));//[ 'constructor', 'toString' ]
console.log(Object.getOwnPropertyNames(Father.prototype));//[ 'constructor', 'toString' ]
console.log(Object.getOwnPropertyNames(a1))//[]空数组